assuming an M112 section piling would be used, with an allowable inter- 

 lock tension of 6^000 pounds per inch, the maximum allowable cell wall 

 radius for this problem, id.th p being the pressure of the saturated cell 

 fill would be 



r ^ 12t - 12 X 6000 

 P. 32h 



=222 feet 



and for safety will be taken as 50 feet. (Note that any pressure due to 

 hydrostatic water pressure has been ignored, i.e. that the water level 

 for maximum interlock tension is at the wall b ase , ) 



312. Stability Calculations - Overturning . - The circular tension 

 per foot of pile developed in the pile interlocks of the outside cell 

 wall is directly proportional to the radius of the wall and to the 

 maximum pressure of the cell fillj that is t « pr, where p is the 

 pressure of the fill. The total tension developed in one interlock is 

 T = t x h/2 s Pr, where P is the total thrust due to the cell fill. 



The tension in the cross wall, if two cells are joined by a standard 

 Y-pile with 120*^ legs is the same as the tensions in the individual 

 wall arcs, that is T s Pr again. 



313. For the cell to overturn, the cross wall piles must slip 

 along the interlocks. Therefore, if f is the coefficient of lock 

 friction, and L is the length of one cell section, the resistance to 

 overturning developed by the cross walls per unit length of structure is 



S == Prf (81) 



^ L 



311+. In addition to this resistance, there is the shear resistance 

 developed by the cell fill itself which is given by S^ - p tan 0, that 

 is, the lateral fill thrust times the coefficient of internal friction. 

 Therefore the total resistance to overturning per unit length of wall 

 developed by the crosswall and cell fill is 



S - Sp -^ S^ (82) 



^^ ^^4^ tan 0) 



315. The exterior overturning moment (M) per unit length of wall 

 about the center of the cell may be replaced by a couple about the neutral 

 axis (also the center of the cell). If it is assumed that pressures along 

 the wall bottom which may cause this couple are linearly distributed 

 along the wall width, the "couple diagram" may be drawn as shown in Figure 

 103. 



153 



